787 Question ?

From what I can tell the crank / counter balancer drive gears are sealed in at the rear of the engine. The manual says to add 1oz of engine oil to the cavity through the fill hole. I have a 97 manual not a 96.

This engine must be an early one as it does not have the fill plug, this oil would then be non serviceable once the cases are assembled. Would it be a good idea to drill and tap the case so I can add a fill plug ?

I can tell you from experience on a 96xp that those counters blow and take out half your case when it happens. I didn't know about the updated cases until i bought a replacement case from a 97xp which has the cap and plug in the bottom. It would be a good idea to put a bunch of silicone around the cap in the back of your counter case. When you get water in your engine that is the lowest point and water usually hangs out there. Over the years the bearings get rusted and then seize up and blow out the side. If you ever rebuild your engine i would get updated cases.

Updated cases are not going to happen as I don't have bottom less pockets to spend on this thing.

What does silicone on the rear plug do ? Help stop water getting to the bearing if the hull gets flooded ?

This motor had never been apart until I got my mits on it and it's in pretty decent shape considering it's probably original. There is a spot on the upper and lower case where the fill plug and drain plug would be on the newer cases just wondering if it's worth drilling and tapping to add these while I have the motor torn apart ? If I do this at least the oil can be changed every year.

Putting oil in the cb cavity is useless because it just gets sucked out by the rear cyl & burned.

It is not a sealed cavity it connects directly to the rear cyl & it gets its lube the same way the crank & rod bearings do. The front cb bearing is sealed & the rear bearing gets lube the same way the crank bearings do.

When building a motor I put a little oil to help at start up to lube the gears.

Putting oil in the cb cavity is useless because it just gets sucked out by the rear cyl & burned.

It is not a sealed cavity it connects directly to the rear cyl & it gets its lube the same way the crank & rod bearings do. The front cb bearing is sealed & the rear bearing gets lube the same way the crank bearings do.

When building a motor I put a little oil to help at start up to lube the gears.

Looking at it again this make sense I even noticed a small hole in the upper case which must help direct the fuel and oil mix onto the gears.

What is the purpose of the drain and fill plugs on the newer cases then ?

I called a seadoo tech and was told that the drain is for water flooded engines. The oil is provided by the gas oil mix. When you drain the water out they do recommend putting some oil in the shaft. My 96 has them so some one must have replaced the engine at one time. I usually put a little 2 cycle synthetic oil in once a season doesn't hurt any thing.